doc: add section on ironside reset handling

Ref: NCSDK-35716
Signed-off-by: Håkon Amundsen <[email protected]>

Author: hakonfam

doc/nrf/app_dev/device_guides/nrf54h/ug_nrf54h20_ironside.rst

@@ -781,6 +781,8 @@ For more information on the boot sequence, see :ref:`ug_nrf54h20_architecture_bo
    The term "secondary slot" and "secondary image" are used in the MCUboot context.
    This usage is unrelated to the "secondary firmware" described in this section.
 
+.. _ug_nrf54h20_ironside_se_secondary_conf_trigger:
+
 Configuration and triggering
 =============================
 
@@ -1012,6 +1014,16 @@ BOOTERROR
   * A non-zero value indicates that an error condition occurred, preventing the CPU from starting.
     Detailed information about the issue can be found in the boot report.
 
+.. _ug_nrf54h20_ironside_se_local_domain_reset:
+
+Local Domain Reset Handling
+****************************
+
+When a local domain resets, |ISE| detects the event in the RESETHUB peripheral and triggers a global system reset, reported as ``SECSREQ`` in the local domain ``RESETINFO.RESETREAS.GLOBAL``.
+
+Certain local domain reset reasons can trigger a boot into the secondary boot mode.
+For more information, see :ref:`ug_nrf54h20_ironside_se_secondary_conf_trigger`.
+
 .. _ug_nrf54h20_ironside_se_boot_commands:
 
 Boot commands